If a compound is made up of more than one element why is it considered a pure substance? Choose 2 Group of answer choices The compound has different properties than the individual elements A compound can not be physically separated A compound can not be chemically separated A compound can be physically and chemically separated

A compound can not be physically separated

Explanation:

A compound is a chemical substance that comprises of atoms of more than one element i.e. two or more elements are chemically combined to form a compound. However, as stated in this question, compounds are referred to as pure substances.

This reason is attributed to the fact that a compound cannot be physically separated i.e. the constituents of a compound cannot be separated using physical changes or methods. This is because the atoms of the constituent elements are combined or joined together by chemical bonds.

answer:

the answer is 6 valence electrons.

explanation:

valence is the # of electrons on the outer most shell of an atom.

oxygen has 6.

although, the valency of oxygen is 2, because it only needs to make 2 covalent bonds, or gain 2 electrons, to achieve the stable octet configuration of a noble gas.

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a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.